Needle clamp and thread guard



Aug. 3, 1937. M.- M. GLASBERG 2,088,852

. NEEDLE CLAMP AND THREAD GUARD Filed April 6, 1936 Patented Aug. 3, 1937 PATENT owl-c1:

NEEDLE CLAMP AND THREAD GUARD Myer M. Glasberg, Revere, Mass.

Application April 6,

M j 5 Claims.

This invention relates to a needle clamp and thread guard such as is used on single needle sewing machines but with particular reference to those operated with a roller presser.

Thread guards are normally used on almost everytype of sewing machine to prevent a flopping of the thread which, unless eliminated, produces eye strain on the operator, irregularity of the stitching, abnormal wear and tear on the it machine, excessive breakage of needles and thread with accompanying physical hazards, destruction of the work resulting from such breakage, loss of time to operator and increased expenses to the manufacturer.

15* To be effective a thread guard must be absolutely positive in its action and never allow a thread to slip out. If it does slip out and becomes free, the above mentioned results reoccur at once. It should also prevent the pinching and.

chafing of the thread between roller presser and needle which is a great source of breakage.

The present most common types of thread guards are made of wire bent into some form of hook or loop and attached either to the needle 25 bar ata point above the needle clamp or on the side or the bottom of the needle clamp itself i and are designed and. intended only to prevent the thread from flopping, thepinching and chafing problems not being considered. "In' the usual sewing machine, the allowable space in which the needle clamp and needlecan operate is definitely, closely and narrowly limited on account of the work which the machine must produce. It is limited on the top by the casting into whichthe needle bar, slides, on the bottom by the throat plate of the machine and on the outside by the roller presser when it is in an operative position adjacent to the needle.

Within these narrow limits, any extra appen- Even should this usual wire guard be adjusted so thatit does not actually strike the machine, the" normal play that soon develops in even a new machine causes these wire guardsto lose {5'5 their adjustment and interfere because due to 1936, Serial No. 73,002

this extra play, the needle bar has to go lower inorder to push the needle farther into the hole in the throat plate to allow the shuttle to come above the needle eye so as to function in sewing.

After further adjusting so that the wire guard just clears the face of the roller presser, the variable, automatic raising of this roller by the varying thickness of the work throws the guard out of adjustment and again into an interfering position where the guard soon breaks off and either breaks or frees the thread.

Likewise when the operator wishes to stop the machine and adjust the work so that he can sew around a sharp corner, he is faced by another problem on account of the usual wire guard with its non-positive adjustment. He must stop the machine just as the needle has passed through the work and into the hole in the throat plate in order to hold the work in place for turning; but if the needle is too low, when the roller presser is raised by the foot lifting lever to allow the work to be turned, the roller on the way up Will again strike the wire guard, bend it and later break it off, and at the same time chafe and break the thread.

If the needle is left high, to avoid the above interference with the roller, it will not be in the hole in the throat plate and the first revolution of the machine usually breaks it off.

It istherefore very important under the present practice for an operator to stop the machine at just the proper place, which is very difficult without any guide, and consumes much time and waste.

In other words, due to these factors, it is almost impossible to keep the present wire guard continuallyadjusted so that it will not interfere with other parts. The results are that the usual wire thread guards are generally bent, then broken and eventually removed. This does not cure the diificulty but only starts a second series of troubles due to the free flopping thread by causing the needle to vibrate, bend and eventually break-01f both thread and needles. In addition to replacing the broken parts, the machine must be rethreaded which consumes time.

At the present time, the concave inside surface of the roller presser comes to a sharp edge against which the needle just rubs. When the roller presser is raised, it has a tendency to catch the thread and force it between its edge and the side of the needle, or the bottom of the guard chafing the thread and breaking it off which makes re- 5 threading necessary. The present type of guard makes no provision to correct this diificulty.

In accordance with my invention, the thread guard contains a slotted hole which entirely surrounds the thread and holds it in a given location rather than the present type of bent wire hook or loop which allows thread to slide around within its confines.

The inner outlet of this hole is as closely adjacent to the needle as is possible instead of being at a distance from it.

The guard is contained within the interior of the needle clamp and not on its exterior.

It has on its lower outside edge a novel protruding toe, peculiar to my invention, which is 'turning up set-screw 3 forcing shank 4 against so designed that whenever it comes in contact with the roller presser under any condition, it

forces it aside a predetermined amount without any special adjustments.

The primary object of my invention is to produce a needle clamp and thread guard which will be absolutely positive in its action of retaining the thread and holding it in a fixed location It will bring the thread closely adjacent and parallel to the needle which allows more accurate and straighter stitching. The thread will have an almost vertical upward pull on the needle point instead of a lateral pull which causes the difficulties already described. The guard will be self contained and an integral part of the needle clamp with no appendices to be bent, broken or adjusted. Its exterior toe will allow it to automatically cooperate with the roller presser to prevent damaging interference as a result of excessive play, or variable thickness of the work, or raising of the roller for turning the work. The thread will therefore never be pinched or chafed between the roller and the needle or the thimble and broken as a result of such chafing; With its use, no special stopping point is required for the machine when changing the direction of the stitching except that the needle be in the hole in the throat plate. It is instantaneously threaded. Preventing and removing all the difficulties described above, it is economical in itself, a time saver, with its associated savings in labor and cost of broken and replaced parts as well as removing the physical hazards to the operators and making their work less fatiguing. It will also eliminate cut fingers due to contact with sharp ends of the bent wires.

This novel needle clamp and thread guard is of the thimble type with a set-screw to fasten it and its associated needle to the needle bar and is preferably made of hardened steel.

Further objects of my invention will hereinafter appear from the following description in connection with the accompanying drawing in which Fig. 1 is a side view partly in vertical section illustrating my guard and its operation in connection with other parts of a sewing machine.

Fig. 2 is a front view of the same. V

Referring to the drawing, the thread guard and protector therein shown as illustrative of one.

embodiment of my invention comprises a thimble I, held in place on needle bar 2, by set-screw 3, placing shank 4 of needle 5 with eye 6 in an operating position. The thread is shown at I, while 8 represents the diagonal guard hole with an aperture 9 in outer surface l0, an opening II in the conical surface of the inside bore I2 and a diagonal slot l3 cut lengthwise in the side of hole 8.

The inside bore is in the form of an inverted funnel with perpendicular and symmetrical sides l4, |5, the latter being prolonged vertically along from its base surface 20 and extending to the side |6,'to base while I4 is intercepted by the conical surface |2.

A protruding toe l8 extends outwardly from aperture 9 on outside surface ID, as at I9, and downwardly from the centre of the base as at 20. 5

The usual roller presser 2| is shown with a concave inner surface 22, outside edge 23, knurled work contact surface 24 and roller arm bracket 25.

Likewise we have the usual throat plate 26 with a hole 21 into which the needle passes.

Needle 5 is clamped to the needle bar 2 by placing needle shank 4 into a recess in the side of needle bar 2 enclosing both in thimble and perpendicular inner surface bore I4.

Roller presser 2|, with an inner concave sur- 'face'22, has an outside knurled edge 24 which presses down on the material being sewed. This roller revolves as the work is moved along by a feeding device in the shuttle case underneath and also in contact with the work.

To get accurate andstraight stitching the outside edge 23 of the roller presserv 2| must be as close to the needle as possible in order to hold the work flatly and firmly against the push and 25 pull of the needle. In normal operation thimble and roller 2| do not interfere. However should thimble go lower than originally, due to play in needle bar 2, or should roller 2 automatically go higher due to thickness of the Work or should roller 2| be raised manually by the so-called foot lifting lever which pulls roller arm bracket 25 vertically upwards to allow room for shifting the work, thimble I does interfere with concave surface 22 of roller 2|.

From the lower portion of the outside surface H] which is opposite to the surface'engaging the set-screw, there is a protruding toe l8 which extends outwardly from surface ID, as at I9, and downwardly from surface IT, as at 20. This toe is designed to slide on concave surface 22 forcing it away from the needle 5. Edge 23 of roller 2| being correspondingly forced away from needle 5 allows clearance for the thread 1 between 23 and 5 thus eliminating the greatest and most frequent sources of pinched, chafed and broken thread.

. In the extra thickness of the toe |8, a conical surface I2 is made within the thimble, starting perpendicular portion of side M of the bore.

, This results in a recess 28 in the bottom of the thimble starting from the base 20, and bounded by the conical surface l2 on one side and the needle shank 4 on the other side.

In the toe l8, a hole 8 is drilled diagonally downward from 9, in surface I9, to II, in surface l2, which brings the aperture adjacent to the needle shank 4.

A diagonal slot I3 is cut from base 20 to the aperture 9 parallel and into hole 8 as a thread inlet into the side of hole 8.

Thread'lis thenslipped through slot |3 into hole 8, thence through recess 28, thence adjacent to needle 5 and edge 23 of roller 2| and thence through the needle eye 6.

Recess 28 has a novel construction feature as it allows hole 8 to be drilled higher on the thimble and ending adjacent to the needle shank and thus also allowing more metal and. corresponding necessary increased strength in toe l8 which in turn is limited in its width and depth by the allowable clearances from other parts of the machine. j

Recess 28 has also a novel operation feature.

As the thread 1 passes through the thimble it follows a smooth curve with contact at only one ,point approximately adjacent to II reducing the strain on the thread. The thread then oscillates between eye 6 and the upper contact point.

Recess 28 allows free oscillation between these two points only, reducing the strain and removing the chafing and breaking of the thread. It also allows the upper contact point to be higher than base H which brings thread I more parallel to the needle reducing the lateral strain on the needle to a minimum. In particular it alsoallows the thread I a means and a place in which to slide to one side when edge 23 comes in contact with toe IE or sometimes bottom surface 2!).

Slot l3 may be either on the right or left side of the outer surface l depending on which side of the machine its take up lever is located and also on the position of the needle bar. A corresponding groove 29 is also made in the face above the diagonal hole 8 in order to allow the thread I to pass in a straighter line to the take up lever.

Having described a preferred embodiment of my invention, I claim:

1. In combination with a needle clamp having a longitudinal bore and an outwardly flaring base, a thread guard formed integrally with said clamp, said guard having a diagonal hole extending downward from the outer surface of said clamp to the inside of its bore, a side wall of said hole being intercepted by a slot cut from the base and at an angle to said base, and a toe projecting outwardly from the side and adjacent to said hole and downwardly from the base and adjacent to said bore, the base of said toe being recessed forming a chamber.

2. In combination with a needle clamp having a longitudinal bore and an outwardly flaring base, a thread guard formed integrally with said clamp, said guard comprising an eye with a diagonal hole extending downward from the outer surface of said clamp to the inside of its bore, and an inlet with a slot cut from the base and intercepting a side of said hole, and a thread protector comprising a projection extending outwardly from below the outside aperture of the eye and downwardly from the base adjacent to said bore, the base of said toe being recessed forming a chamber.

3. A needle clamp having a longitudinal bore, an outwardly flaring base and a diagonal hole extending downward from the outer surface of said clamp to the inside of its bore, said base having a slot cut at an angle thereto and intercepting one side of said hole, and a toe projecting outwardly from the side and adjacent to said hole and downwardly from the base and adjacent to said bore, said bore having an inverted funnel shape forming a recessed chamber, being perpendicularly and symmetrically cylindrical on top and joining a distorted cone on the bottom, one side of said distorted cone being a prolongation of the cylindrical top and the other side being a portion of a truncated cone.

4. In combination with a needle clamp a thread guard having a longitudinal inverted funnel shaped bore and an outwardly flaring base, said bore forming a chamber in said base, a diagonal hole extending downwardly and inwardly from the outer surface of said clamp to the top of the sloping side of said inverted funnel shaped bore, and a toe projecting outwardly from the side and adjacent to said hole and downwardly from said base and adjacent to said bore, the inner opening of said hole being at the apex of said chamber and above the plane of said base, said base having a slot cut at an angle thereto and intercepting one side of said hole.

5. In combination with a needle clamp a thread guard having a longitudinal inverted funnel shaped bore and an. outwardly flaring base, said bore being perpendicularly and symmetrically cylindrical on top and joining a distorted cone on the bottom, one side of said distorted cone being a prolongation of the cylindrical top and the other side being a portion of a truncated cone forming a chamber in the base, a diagonal hole extending downwardly and inwardly from the outer surface of said clamp to the top of the sloping side of said inverted funnel shaped bore, and a toe projecting outwardly from the side and adjacent to said hole and downwardly from said base and adjacent to said bore, the inner opening of said hole being at the apex of said chamber and above the plane of said base, said base having a slot cut at an angle thereto and intercepting one side of said hole.

MYER M. GLASBERG. 

